docs: def _create_xml_node(cls):
          """Create XML node from "_xml_map".
          """
          try:
              xml_map = cls._xml_map
          except AttributeError:
              raise ValueError("This model has no XML definition")
  
          return _create_xml_node(
              xml_map.get('name', cls.__name__),
              xml_map.get("prefix", None),
              xml_map.get("ns", None)
          )